Join Date: Jun 2010
Location: Northern Virginia
Unfortunately, the feeder fish you've posted is a common goldfish. Common goldfish get extremely large and have very different water requirements from tropical fish. They are coldwater animals, so they are adapted to an oxygen rich environment without much exposure to heat. Warmer water puts a lot of strain on their systems, and cannot hold as much oxygen as cold water can, so they have trouble getting enough oxygen.
The best thing for you to do with this fish temporarily will be to get a large tank or sterilite/rubbermaid plastic storage bin. They make huge ones for very little money. Stack one inside the other so the sides don't bow out and get the largest filter you can for it. Ideally, for a goldfish, you want a filter that has a gph that is 10x the gallonage of the tank. For instance, if the tank is 30G, you want a 300gph filter.
This is only a temporary fix. The reality of the situation is that common goldfish are not suited to live in aquariums--they are pond fish. They get way too large to be practical in someone's home, and they're extremely social animals that shouldn't live life of isolation. At some point, hopefully sooner than later, you are going to have to find someone with a pond for the fish to live in along with other common goldfish. I suggest posting an ad on your local craigslist or looking for a local aquarium society or club--many will allow you to post on their forums and attend meetings without ever paying dues.
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